Hi Ramzi,
Good question!
**Answer Calls - When a call is forwarded to UC these Ports answer the call and play the user Greeting;
Check this check box to designate the port for answering calls. These calls can be incoming calls from unidentified callers or from subscribers.
Message Notification - Call to Outcall device (like Mobile) to indicate new messages for Subscriber;
Check this check box to designate the port for notifying subscribers of messages. Assign Message Notification to the least busy ports.
**Dialout MWI - Must have to turn On/Off the RED Message Lamps
Check this check box to designate the port for turning MWIs on and off. Assign Dialout MWI Requests to the least busy ports.
TRAP Connection - TRAP Connection - One such application is the Media Master Control;
Check this check box so that subscribers can use the phone as a recording and playback device in Cisco Unity web applications and e-mail clients. Assign TRAP Connection to the least busy ports.
http://www.cisco.com/en/US/docs/voice_ip_comm/unity/5x/integration/cucm_sccp/guide/cuintcucmskinny020.html
Hope this helps!
Rob